kernel/linux.git/include/net/act_api.h, branch v6.12.107

net/sched: act_gact, act_police: range check the fallback control action

2026-08-19T16:14:27+00:00

commit 883b56ae58fe657d8497806c7059646e9ba6dbd0 upstream. tcf_action_check_ctrlact() range checks the primary control action: if (!opcode) ret = action > TC_ACT_VALUE_MAX ? -EINVAL : 0; TC_ACT_VALUE_MAX is TC_ACT_TRAP, so kernel-internal verdicts above it cannot be set that way. But act_gact and act_police each carry a second, independent control action supplied by user space that never reaches that helper - TCA_GACT_PROB.paction and TCA_POLICE_RESULT. Both only reject TC_ACT_GOTO_CHAIN, so any other value is stored verbatim and returned verbatim from the action. In particular user space can store TC_ACT_CONSUMED, which is TC_ACT_VALUE_MAX + 1 and is deliberately not part of the UAPI value range. That verdict tells every caller the action took ownership of the skb, so nobody frees it: sch_handle_ingress(), sch_handle_egress() and tcf_qevent_handle() all deliberately skip the free for it. The result is one leaked sk_buff plus its data buffer per packet traversing the filter, unbounded, for all traffic on the chain including kernel-generated packets. Both are trivially deterministic. act_gact clamps tcfg_pval to >= 1, so with pval = 1 gact_determ() returns the fallback for every packet. act_police has no mandatory rate, so rate = 0 leaves tcfp_mtu = ~0 and tcf_police_mtu_check() always passes. TC_ACT_CONSUMED was added by commit 720f22fed81b ("net: sched: refactor reinsert action"), after both goto-chain guards were written: commit 9469f375ab09 ("net/sched: act_gact: disallow 'goto chain' on fallback control action") and commit c08f5ed5d625 ("net/sched: act_police: disallow 'goto chain' on fallback control action"). Neither guard was widened when the new verdict appeared. Factor the existing range test out of tcf_action_check_ctrlact() as tcf_action_valid() and apply it to both fallbacks. The helper cannot call tcf_action_check_ctrlact() directly because that also allocates a goto_chain, which is exactly what these two sites must not do. Reproduced on v7.2-rc6: kmemleak reports one leaked 232-byte skbuff_head_cache object plus its 704-byte data buffer per packet. With this patch both configurations are rejected with -EINVAL and kmemleak reports none. Fixes: 720f22fed81b ("net: sched: refactor reinsert action") Cc: stable@vger.kernel.org # v5.3+ Signed-off-by: Hyunjung Ko Acked-by: Jamal Hadi Salim Tested-by: Victor Nogueira Link: https://patch.msgid.link/20260806101252.809593-1-hj351016@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/sched: act_api: use RCU with deferred freeing for action lifecycle

2026-06-19T11:42:19+00:00

[ Upstream commit 5057e1aca011e51ef51498c940ef96f3d3e8a305 ] When NEWTFILTER and DELFILTER are run concurrently it is possible to create a race with an associated action. Let's illustrate with CPU0 running NEWTFILTER and CPU1 running DELFILTER: 0: mutex_lock() <-- holds the idr lock 0: rcu_read_lock() 0: p = idr_find(idr, index) <-- action p is valid (RCU protects IDR) 0: mutex_unlock() <-- releases the idr lock 1: refcount_dec_and_mutex_lock() <-- refcnt 1->0, mutex held 1: idr_remove(idr, index) <-- Action removed from IDR 1: mutex_unlock() <-- mutex released allowing us to delete the action 1: tcf_action_cleanup(p); kfree(p) <-- Kfrees p immediately, no deferral 0: refcount_inc_not_zero(&p->tcfa_refcnt) <-- ouch, UAF p points to freed memory This patch fixes the race condition between NEWTFILTER and DELFILTER by adding struct rcu_head to tc_action used in the deferral and introducing a call_rcu() in the delete path to defer the final kfree(). Note: this is a revert of commit d7fb60b9cafb ("net_sched: get rid of tcfa_rcu") but also modernization/simplification to directly use kfree_rcu(). Let's illustrate the new restored code path: 0: rcu_read_lock() 1: refcount_dec_and_mutex_lock() <-- refcnt 1->0, mutex held 1: idr_remove(idr, index) 1: mutex_unlock() 1: call_rcu(&p->tcfa_rcu, tcf_action_rcu_free) <-- defer kfree after grace period 0: p = idr_find(idr, index) 0: refcount_inc_not_zero(&p->tcfa_refcnt) <-- fails, refcnt already 0 1: rcu_read_unlock() <-- release so freeing can run after grace period After CPU1 calls idr_remove(), the object is no longer reachable through the IDR. CPU0's subsequent idr_find() will return NULL, and even if it still held a stale pointer, the immediate kfree() is now deferred until after the RCU grace period, so no UAF can occur. Fixes: d7fb60b9cafb ("net_sched: get rid of tcfa_rcu") Suggested-by: Jakub Kicinski Reported-by: Kyle Zeng Tested-by: Victor Nogueira Tested-by: syzbot@syzkaller.appspotmail.com Signed-off-by: Jamal Hadi Salim Tested-by: Kyle Zeng Reviewed-by: Pedro Tammela Reviewed-by: Eric Dumazet Reviewed-by: Victor Nogueira Link: https://patch.msgid.link/20260531160812.68020-1-jhs@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks

2026-03-13T16:20:47+00:00

commit 11cb63b0d1a0685e0831ae3c77223e002ef18189 upstream. As Paolo said earlier [1]: "Since the blamed commit below, classify can return TC_ACT_CONSUMED while the current skb being held by the defragmentation engine. As reported by GangMin Kim, if such packet is that may cause a UaF when the defrag engine later on tries to tuch again such packet." act_ct was never meant to be used in the egress path, however some users are attaching it to egress today [2]. Attempting to reach a middle ground, we noticed that, while most qdiscs are not handling TC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we address the issue by only allowing act_ct to bind to clsact/ingress qdiscs and shared blocks. That way it's still possible to attach act_ct to egress (albeit only with clsact). [1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/ [2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/ Reported-by: GangMin Kim Fixes: 3f14b377d01d ("net/sched: act_ct: fix skb leak and crash on ooo frags") CC: stable@vger.kernel.org Signed-off-by: Victor Nogueira Acked-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260225134349.1287037-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/sched: Add helper macros with module names

2024-02-02T18:57:55+00:00

The macros are preparation for adding module aliases en mass in a separate commit. Although it would be tempting to create aliases like cls-foo for name cls_foo, this could not be used because modprobe utilities treat '-' and '_' interchangeably. In the end, the naming follows pattern of proto modules in linux/net.h. Signed-off-by: Michal Koutný Acked-by: Jamal Hadi Salim Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20240201130943.19536-2-mkoutny@suse.com Signed-off-by: Jakub Kicinski

net/sched: simplify tc_action_load_ops parameters

2024-01-07T14:58:26+00:00

Instead of using two bools derived from a flags passed as arguments to the parent function of tc_action_load_ops, just pass the flags itself to tc_action_load_ops to simplify its parameters. Reviewed-by: Jiri Pirko Signed-off-by: Pedro Tammela Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller

net/sched: introduce ACT_P_BOUND return code

2024-01-04T02:36:24+00:00

Bound actions always return '0' and as of today we rely on '0' being returned in order to properly skip bound actions in tcf_idr_insert_many. In order to further improve maintainability, introduce the ACT_P_BOUND return code. Actions are updated to return 'ACT_P_BOUND' instead of plain '0'. tcf_idr_insert_many is then updated to check for 'ACT_P_BOUND'. Signed-off-by: Pedro Tammela Acked-by: Jamal Hadi Salim Link: https://lore.kernel.org/r/20231229132642.1489088-1-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: act_api: skip idr replace on bound actions

2023-12-14T01:53:59+00:00

tcf_idr_insert_many will replace the allocated -EBUSY pointer in tcf_idr_check_alloc with the real action pointer, exposing it to all operations. This operation is only needed when the action pointer is created (ACT_P_CREATED). For actions which are bound to (returned 0), the pointer already resides in the idr making such operation a nop. Even though it's a nop, it's still not a cheap operation as internally the idr code walks the idr and then does a replace on the appropriate slot. So if the action was bound, better skip the idr replace entirely. Signed-off-by: Pedro Tammela Acked-by: Jamal Hadi Salim Reviewed-by: Vlad Buslov Link: https://lore.kernel.org/r/20231211181807.96028-3-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: Rename user cookie and act cookie

2023-02-21T00:46:10+00:00

struct tc_action->act_cookie is a user defined cookie, and the related struct flow_action_entry->act_cookie is used as an handle similar to struct flow_cls_offload->cookie. Rename tc_action->act_cookie to user_cookie, and flow_action_entry->act_cookie to cookie so their names would better fit their usage. Signed-off-by: Paul Blakey Reviewed-by: Marcelo Ricardo Leitner Signed-off-by: Jakub Kicinski

net/sched: move struct action_ops definition out of ifdef

2022-12-09T09:18:07+00:00

The type definition should be visible even in configurations not using CONFIG_NET_CLS_ACT. Signed-off-by: Pedro Tammela Reviewed-by: Jamal Hadi Salim Reviewed-by: Victor Nogueira Signed-off-by: David S. Miller

act_skbedit: skbedit queue mapping for receive queue

2022-10-25T08:32:40+00:00

Add support for skbedit queue mapping action on receive side. This is supported only in hardware, so the skip_sw flag is enforced. This enables offloading filters for receive queue selection in the hardware using the skbedit action. Traffic arrives on the Rx queue requested in the skbedit action parameter. A new tc action flag TCA_ACT_FLAGS_AT_INGRESS is introduced to identify the traffic direction the action queue_mapping is requested on during filter addition. This is used to disallow offloading the skbedit queue mapping action on transmit side. Example: $tc filter add dev $IFACE ingress protocol ip flower dst_ip $DST_IP\ action skbedit queue_mapping $rxq_id skip_sw Reviewed-by: Sridhar Samudrala Signed-off-by: Amritha Nambiar Signed-off-by: Paolo Abeni